As illustrated in FIG. 1, which is a network structure of a Long Term Evolution-Advanced (LTE-A) system, an eNodeB (eNB) is connected to a Core Network (CN) via a wired interface, a Relay Node (RN) is connected to the eNB via a radio interface, and a User Equipment (UE) is connected to the RN or the eNB via a radio interface.
A communication link between the RN and the eNB is referred to as a backhaul link, and a link between the RN and the UE is referred to as an access link.
The following two channels are defined in the LTE-A system:
a Relay-Physical Downlink Control Channel (R-PDCCH) is a control channel over which the eNB transmits data to the RN over the backhaul link; and
a Relay-Physical Downlink Shared Channel (R-PDSCH) is a physical shared channel over which the eNB transmits data to the RN over the backhaul link.
For a common R-PDCCH, a common reference signal, instead of a dedicated reference signal (DRS), has to be provided to a plurality of RNs for use in demodulation and currently occupies resource locations as illustrated in FIG. 2. The RN has to demodulate data over the R-PDSCH with a demodulation reference signal (DMRS).
In FIG. 2, the first three columns in a timeslot 1 form a Physical Downlink Control Channel (PDCCH) zone, an R-PDCCH zone includes the fourth and fifth columns, or the fourth, fifth and sixth columns, or the fourth, fifth, sixth and seventh columns in the timeslot 1, and an R-PDSCH zone includes all of columns in a timeslot 2 and unoccupied columns in the timeslot 1.
The inventors have identified, during making of the invention, the following technical problem in the prior art.
In the LTE-A system, the eNodeB transmits no demodulation reference signal (DMRS) in the R-PDSCH zone so that the RN can not perform channel estimation on the R-PDSCH with a demodulation reference signal and consequently can not receive correctly data over the R-PDSCH.